The Hebrew Calendar

And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years.

Genesis 1:14 KJV

Nothing God gave to man has been used so consistently for the purpose he intended. Every civilization of man has used the sun, the moon, or both for the demarcation of time. They had no choice. Even a hunting society had to take notice of the passage of seasons. When would the animals migrate to the north and when would they return? How soon would the antlered animals make their move down from the high country? No people dependent upon the land could fail to notice that there was a time to plant and a time to harvest. Their problem was the prediction of that time, and that required the observation of the sun. It required a calendar, and some form of calendar has always been a mark of civilization.

A calendar is more than a pretty picture with the days of the month laid out below. A calendar is a system of determining the beginning and ending of the year and dividing it up into seasons, months, weeks, and days. To be of any use at all, it has to be done in advance. A calendar from the past is no more than a diary. By its very nature, a calendar is predictive, and this is why the sun and the moon are so very useful – they are the most predictable elements in the environment of man.

We have no record of when man first noticed this, but it was a very long time ago. Even if he lost everything else God gave him, it is inconceivable that intelligent man – in the space of a lifetime living and working in the out of doors – would not come to know intimately the cycles of the sun, moon, and stars. He would be able to pass on to his children and grandchildren the exact location of sunset on the longest and shortest days of the year. Early on he would have figured out that the sun made that cycle regardless of what his priest said or did – his observations of the sun were not mere superstition.

This was quite a simple task for a man and his family. It became a bit more complicated with clans, communities, and ultimately, civilizations. Consider the problem. How would you go about setting up a calendar – a predictable calendar – for a small community? One of the simplest approaches is merely to count the moons. The American Indians did it this way.

But there is a problem with determining the year. The Islamic calendar is based solely on the moon with no corrections for the movement of the sun. It may not matter much in the desert that the seasons shift slowly forward through the calendar year, but it matters very much to a society dependent on grain and fruit crops. Most ancient calendars took account of the moon, but the problem they had to solve was the movement of the sun. It was not a particularly difficult problem, but it required some thought.

If we were to tackle this problem, we would first have to choose a place to make our observations. We would soon learn that moving about would lead to inaccurate observations. We could put a stick in the ground at the observation point, and then place another stick in the ground on a direct line with the sun when it rises. We could do this every day, and in the space of one year, we would have an arc of sticks that shows the exact point of sunrise on every day of the year. The northernmost stick would designate the day of the summer solstice, and the southernmost stick the winter solstice. The stick in the middle of the line would designate the equinox.

So far, this is a piece of cake. If someone asks, “What day is this?” all we have to do is run out to our line of sticks the next morning and check it out. Naturally, there are problems. What if an animal or a rainstorm dislodges some of our sticks? What if some prankster from a neighboring clan rearranges them? The people of the Salisbury Plain who built Stonehenge found a drastic, but effective solution to that problem.

No one knows who they were. Every vestige of the civilization around Stonehenge is gone except one – a circle of giant stones on a piece of level high ground in Southern England. It is plain that they took great pains to observe and predict the movement of the sun and moon. Stonehenge may or may not have been a place of worship, but it was certainly an observatory from which a calendar was devised and maintained.

It depends on which archaeologist you consult, but between the death of Noah (about 2,000 B.C.) And the death of Abraham (about 1,800 B.C.), a people moved into the Salisbury Plain in Southern England and proceeded to tackle the problem of constructing a calendar. We cannot be certain as to why they did some of the things they did, or even in what order; but there was a logic that we could follow today with the same results.

One of the first things they did was to dig 56 pits arranged in a circle some 240 feet in diameter. This might have resulted from going out at sunrise every 13 days and digging a pit on a line with sunrise and sunset. Having no doubt noticed the North Star never moved, they oriented the circle by building two mounds on the north and south axis of the circle.

By means of careful observation, they determined the point on the horizon where the sun rose at its northernmost point. This was the summer solstice – the longest day of the year. Outside their circle of stones, on a direct line with the sunrise, they placed a stone. This was not just any stone. Taking no chances on having animals, elements, or man alter the arrangement, they set up a 35 ton block of Sarsen sandstone – brought from 20 miles away. It is still in place nearly 4,000 years later.

Whoever these people were, they proceeded to mark other points of the compass – the winter solstice, the equinoxes – with stones, and to build earthworks around their observatory. It would have been a remarkable project in any age, but it is nothing short of astonishing for the time in which it was done. Plainly, the calendar was of great importance to these people.

Stonehenge was modified occasionally over succeeding generations. Bluestones weighing up to 50 tons were brought from Southwest Wales, and set up in concentric circles, once again aligned with the heavens. Two circles created in the earliest time contained 29 and 30 stones, respectively. The lunar month is about 29 ½ days, so it seems they made their months 29 and 30 days long.

There are two very important observations about Stonehenge. One is that a calendar based on the sun and the moon was one of the earliest achievements of civilized man. The other is the heroic efforts these people made to create and preserve their calendar. Of all the things that they might have done, all that is left is a circle of stones that has lasted for over 4,000 years – their calendar.

The people of Mesopotamia faced a different problem. Living in an alluvial plain, high ground was scarce and large stones nonexistent. They solved the problem by building their own “high ground.” The land is dotted with the remains of ancient towers. From the tops of these towers, the horizon could be marked with the location of the winter and summer solstice.

The Bible describes a tower like this, including the building material and the reason for building it. The tower is the infamous Tower of Babel: “And they said, Go to, let us build us a city and a tower, whose top may reach unto heaven; and let us make us a name, lest we be scattered abroad upon the face of the whole earth” (Genesis 11:4 KJV).

The words “may reach” are not in the Hebrew text. They did not build the tower to reach heaven, but rather to observe the heavens. One source observed that there are frequent winter ground fogs along the Tigris and Euphrates rivers, and the towers enabled them to get above the fog for calendar observations.

We do know that the ancient Sumerians and Babylonians observed the heavens, and there is evidence that they oriented at least some of their towers to the heavens. We also know that they based their calendar systems on the movement of sun and moon. The people of Erech in Mesopotamia invented writing, and evidence of calendars was found in the ruins along with the earliest writings of man.

The Bible tells us that Noah settled in this region after the Great Flood, and we know that he brought a calendar with him. The years of Noah’s calendar were reckoned from his birth: “In the six hundredth year of Noah’s life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened” (Genesis 7:11 KJV). There are several calendar references in the account of the Flood, including a seventh month, a tenth month, and the first and second months of Noah’s 601st year. There is one curious footnote – a period of five months is numbered at 150 days. It seems that Noah used 30 day months. A true lunar month would have alternated between 29 and 30 days, but there is probably no special significance in this. During this period of time, Noah may simply have been unable to observe the moon, and adopted a 30 day month. This would have required some adjustment once they left the ark and were once again able to see the moon, but then only Noah’s family had reason to concern themselves with it. (There is no evidence to suggest that the lunar orbit was that different in Noah’s day – rather the contrary.)

It was also from Mesopotamia that Abraham and his descendants came. There is no reason to doubt that Abraham, Isaac, and Jacob had a 12-month lunar calendar that was periodically adjusted for the movement of the seasons. They came from a civilization with a calendar like that.

So when God later spoke to the children of Israel and said, “This month shall be unto you the beginning of months” (Exodus 12:2), they did not have to ask, “Lord, what is a month?” Their people had used a calendar system from time immemorial.

But when God gave this instruction, He did not say “month,” or even “moon.” He used the Hebrew word for “new moon.” Used throughout the Old Testament, it identifies the starting point for the Hebrew month. In fact, nearly all the ancient civilizations used the new moon rather than the full moon for the beginning of the month.

But in deciding to use the new moon, they still had questions to answer. What, for example, constituted the “new moon”? Logic falls out quickly in favor of the observation of the first sliver of the crescent moon, but what if we can’t see it? It could be overcast, or there might be other conditions that prevent accurate observation. We usually think of seeing the new moon right after sunset, but it can occur at any time of the day. By one definition, the moon is “new” immediately after the conjunction, whether we can see it or not.

The ancients learned very early how to calculate the conjunction (that is, the precise moment when the moon passes the sun as they both pass through the heavens). The Hebrews called this moment the molad. Having this piece of information, what were they to do about the “new moon”? Was it the day when the conjunction took place, or the day after? Sometimes they could see the first crescent of the moon on the day of the conjunction, and sometimes not – even in clear weather. It varied with the weather, the time of day of the conjunction, the time of sunset, the relative position of the sun and moon, and the location of the observer.

It would not be very difficult to design a system for determining the new moons. All we need is a set of rules. The first rule could be that the official day of the new moon is the first day that the new crescent is visible right after sunset. This has a lot of appeal. But we do have to allow for problems. What do we do if it is cloudy? That is not terribly difficult. Since lunar months can only be 29 or 30 days long, we can simply alternate when we can’t see the moon. If last month was 30 days long, we’ll just make this one 29. This will work fine most of the time – providing that we are all in the same location. If it is cloudy here and clear a thousand miles from here, we might often declare the new moon on different days. I suppose this could be acceptable if we don’t all have to be together on everything.

If I could calculate the conjunction, and if it were up to me, I might simply declare that the day of the conjunction was the day of the new moon – no adjustments, no confusion. My problem is that I have no authority for one system over the other. The rules are easy to write – the problem is, who writes the rules?

Naturally, we would expect to turn to the Bible to see what the law told Israel to do. The problem is that the law didn’t tell them. While there are plenty of indirect calendar references in the law, instructions about the calendar itself are almost nonexistent. In fact the only explicit instruction about the calendar is Exodus 12:2, “This month shall be your beginning of months; it shall be the first month of the year to you.”

It may be hard to believe, but everything else we know about the calendar, we know from inference or from tradition. For example, how can you tell from the text just quoted which month was the first month? What time of year was it? Jewish tradition tells us it was in the spring, but the only help we get from the Bible is the name of the month: “And Moses said unto the people, Remember this day, in which ye came out from Egypt, out of the house of bondage; for by strength of hand the LORD brought you out from this place: there shall no leavened bread be eaten. This day came ye out in the month Abib” (Exodus 13:3, 4).

And so we know the Hebrew name of the month – Abib. And we know that Abib means, “green ears.” From other Scriptures we learn that the green ears in question were barley, so we infer that the month Abib is the month when there are green ears of barley in the field.

All this is very clever of us, but it is curious that something so important was left to inference instead of being stated. Instructions for sacrifices are laid out in excruciating detail. Why were the instructions for the calendar not done the same way? Naming a month after green ears of barley is better than nothing, but it leaves a lot of unanswered questions. What if the ears are not green until the last day of the month? How would you have known to make that month Abib? Okay, we can decide that the month following the onset of green ears is Abib. But what if the ears turn green on the second day of the new moon? Will they still be green the following month? The ears will often be green in two consecutive months. Which is Abib?

The Bible does not explain, and we seem to be left to figure out for ourselves how to do it. And yet this decision is critical, because the month of Abib is the beginning of the religious year (the civil year seems to have begun in the autumn).

The calendar of the Hebrews was not simply lunar, and it was not exactly lunisolar. The sun only indirectly affected their calendar. The Israelites did not merely observe the sun to calculate their calendar. They observed the crops and the weather.

The problem was that a 12 month lunar year falls some 11 days short of the solar year. So, when the lunar year had fallen about 30 days short, they simply added a 13th month to keep the Passover in the spring. Talmudic sources tell us that the calendar committee did not rely solely on calculation, but on observation as well. They added a 13th month “when the barley in the fields had not yet ripened, when the fruit on the trees had not grown properly, when the winter rains had not stopped, when the roads for Passover pilgrims had not dried up, and when the young pigeons had not become fledged.” i

The leap years were reasonably predictable. If they had just added a 13th month, they could be sure they would not have to do that for the next two years. Early on, they noticed a 19 year cycle in which the leap years occurred on a repeating basis. Reasons suggest that they rarely had to fall back on observation to announce a leap year. Observation could confirm, but it came too late to predict. If they could not predict, how could pilgrims know when to leave home to arrive in time for the festival season. The determination of the calendar had serious practical considerations as well as religious implications.

Where did they find all this in the law? They didn’t. In fact, they found nothing at all about calendar adjustments, leap years, 13th months, conjunctions and new crescents. The children of Israel found in the law a presumption of a calendar and the sanctification of certain days in that calendar. We do not know whether God revealed it to them, or whether they had to figure it out for themselves. All we have is the calendar tradition they have preserved for us along with the sacred Scriptures.

Paul may have been talking about this sort of thing when he spoke of the “oracles” of God. In writing about the Jews and their relationship with God, he asked, “What advantage then has the Jew, or what is the profit of circumcision? Much in every way! Chiefly because to them were committed the oracles of God” (Romans 3:1-2). The word for “oracles” is the Greek logion which means, literally, “sayings.” The Jews retained an oral law besides the written law we find in the Bible, and that oral law included a complex calendar system into which God placed all the holy days of the sacred year.

The modern Hebrew calendar is sometimes challenged because the “new moon” may be postponed one or two days based on a complex set of rules. Actually, these rules are applied only once in the year – on the first day of the seventh month – the Feast of Trumpets. This particular moon (the beginning of the civil year) is determined and then all the others are established by it. Since a cycle of the moon is about 29 ½ days (plus 44 minutes), the first seven months of the religious year (in which all the holy days occur) simply alternate between 29 and 30 days. The extra 44 minutes creates an extra day at predictable intervals, and that is handled by having two consecutive 30 day months from time to time. In order to keep confusion to a minimum, those months are always in the second half of the year.

The objections to the Jewish custom come in two forms: one argues that any postponement from the conjunction is wrong, and the other argues that only the observed new crescent can start a month. But we recall at this point that the Bible does not define a new moon either way. If it did, I suppose there would be no argument.

In calculating the new moon of the Feast of Trumpets, the pivotal point of the Jewish year, the rules proclaim the new moon on the day of the conjunction with some exceptions. For example if the conjunction occurs after noon, the new moon is “postponed” to the following day. In fact, the first new crescent will almost certainly be observed the following day.

This rule generally satisfies those who want the month to begin with the observed new crescent. But there is another rule they find more troubling. When the conjunction occurs on a Sunday, Wednesday, or Friday, the official new moon (and the Feast of Trumpets) is postponed to the following day for religious reasons. The religious requirements are that the Day of Atonement (Yom Kippur) must not fall on the day before or after a Sabbath, and the day before the Last Great Day of the autumn feast cannot fall on a Sabbath. (There are other postponements required because of mathematical consequences of the first two.)

But can “religious requirements” take precedence over the law? In some cases, yes. When the Pharisees challenged Jesus and his disciples over Sabbath observance, he asked them, “Or have you not read in the law that on the Sabbath the priests in the temple profane the Sabbath, and are blameless?” (Matthew 12:5). In other words, the priest had to carry on the work of the sacrificial system even on the Sabbath day. This created a conflict between the sacrificial law (which required sacrifices every day) and the Sabbath (which required that no work be done).

We would normally assume that when laws come into conflict the lesser law would give way to the greater. There can be no greater law than the Ten Commandments, and yet the sacrificial law superseded even the Sabbath. The priesthood had special responsibilities on the holy days and the new moons, so it would not be surprising if they should take those duties into account when working out their calendar rules – especially when the law gave them no specific instructions to the contrary. They had a modest requirement to make a morning and evening sacrifice (each one a lamb) every day of the year. In addition, each Sabbath day they sacrificed two more lambs with meal, oil, and drink offerings (Numbers 28:9). All this work increased dramatically on the day of the new moon. On the first of every month, they were required to sacrifice ten animals – two young bullocks, one ram, and seven lambs – plus the other offerings. It is easy to see the importance of predictability when there is this much work to be done.

Each of the annual holy days also had special offerings. On the Day of Atonement, for example, the prescribed offering was one bullock, one ram, seven lambs, plus any prescribed meal, oil, and drink offerings, and a special goat for a sin offering. Since the Day of Atonement is a fast day, it should not be surprising if steps were taken to avoid it falling before or after a Sabbath day. One can, of course, argue to the contrary, but there is no biblical authority that prevents the rules of the calendar from being written this way.

We don’t know with any precision when the rules for postponements came to be. They seem to have coalesced in their present form in the 10th century, but the principles underlying them are much older. There is evidence dating from much earlier that the authorities “adjusted” their observations to avoid having Yom Kippur fall just before or just after a Sabbath. It was no great trick. They just changed the observation point.ii

Does all this seem confusing to you? Never mind, it seems confusing to a lot of people. The reason most calendar calculations seem complex is because they are trying to give the illusion of precision. The truth is that the solar system is not precise. The moon is not always the same distance from the earth, and there are subtle variations in the time of its orbit. In the nature of things, a calendar is only a rough measure of time.

But suppose it was not God’s intent to impose a new calendar system, but to reveal to Israel where, in their calendar system, his holy days were to fall? He does not tell them what constitutes a new moon, how many days there are in a month, how many months in a year, or how to adapt the lunar calendar to the solar year. Presumably, they already knew how to do that. Other peoples of the time knew, so there is no reason to suppose the Hebrews did not.

This may be a good place to deal with the concept of “holy time.” The idea is that from creation there were certain segments of time set apart and designated as holy. The Sabbath day is said to be “holy time” as are all the annual holy days.

The problem with this lies in our concept of time. Suppose that just after sunset when the Sabbath has begun, you decide to telephone your mother, who lives a continent away from you. It is three hours earlier there, yet both still converse in the same moment in time. For you, it is the Sabbath, but not for her. She may be trying to get you off the phone so she can finish her housework before the Sabbath.

Since the Sabbath day begins at sunset, it does not begin at all places at the same time. How, then, can the Sabbath be “holy time”? In truth, the Sabbath is not holy time, it is a holy day. There is a difference. We in the United States keep the same Sabbath day as the Jews in Jerusalem, but we don’t keep the same window of time.

Therefore the concept of “holy time” is probably misleading, especially pertaining to the annual holy days. The presumption is that the time when the earth reaches a certain point in its orbit around the sun is holy. The astronomer will see an immediate problem. The earth is not always at sunset when it reaches this special place. For the time to be holy, the rotation of the earth on its axis and the revolution of the earth around the sun would have to be synchronous. That is, the sun should always be setting as the earth comes to the place in its orbit that corresponds to the beginning of holy time. It is not.

What does it take to make a day holy? When Moses encountered the burning bush, God told him to take off his shoes for the ground he stood on was holy. The ground was not holy of itself; it was holy because God was there. The Tabernacle was not holy until God entered it and filled it with His presence. The spot where the Temple was built was only a threshing floor until Solomon built a temple on the spot and God entered it.

Both the Tabernacle and the Temple were built by human hands. True, God gave them specifications, but it was left to them to build. We know that God inspired the craftsmen, but we still have to guess what certain parts of it looked like. As long as the Temple was a building built by craftsmen, it was only a building. It was when God entered it that it became holy.

In the same way, the rules of the calendar were written by men. The days of the year were not holy until selected by God. They are, in a sense, made holy by his presence. He told Israel what days in their calendar he would be present – what days he would meet with them. (The old expression “Tabernacle of the Congregation” actually means “Tent of Meeting.”)

Did God give specifications for the calendar like he gave specifications for the Temple? We don’t know. We do know that the Israelites got more from God than the book we call the Bible. The writer of the book of Hebrews opens his account by telling us that God spoke to the fathers in time past at “sundry times and in diverse manners.” The Old Testament contains much, but not all of that communication. The leaders of God’s people commonly consulted God about questions and judgments, and they got answers that are sometimes recorded for us – sometimes not.

We don’t know whether Israel’s calendar was an old calendar appropriated by God, or a new calendar revealed by God. What we do know is that the calendar became authoritative when God proclaimed certain days in it as his festivals. The days were not intrinsically holy – they were made holy.

We also know that God established an administration to go with the law. It may come as a surprise to learn that the law did not answer all questions pertaining to human relationships – not even of man’s relationship with God. When Moses complained to God about the burden of leading the people of Israel, God gave him a solution:

And the LORD said unto Moses, Gather unto me seventy men of the elders of Israel, whom thou knowest to be the elders of the people, and officers over them; and bring them unto the tabernacle of the congregation, that they may stand there with thee. And I will come down and talk with thee there: and I will take of the spirit which is upon thee, and will put it upon them; and they shall bear the burden of the people with thee, that thou bear it not thyself alone. . . And the LORD came down in a cloud, and spake unto him, and took of the spirit that was upon him, and gave it unto the seventy elders: and it came to pass, that, when the spirit rested upon them, they prophesied, and did not cease (Numbers 11:16-25 KJV).

This is the origin of the “seventy elders” of Israel – the basis of the later Sanhedrin – charged with the responsibility of administering the Law of God. We don’t know what they did about the calendar, but we do know that the rules and observations of the calendar were, in the days of Jesus’ ministry, in the hands of the Sanhedrin. We also know that in spite of all the issues where Jesus opposed the Jewish leadership, he never argued with them about the calendar.

It is important for us to understand that, from the beginning, there was an authoritative judiciary in Israel charged with the responsibility of deciding points of law for the people. This system is described in Deuteronomy 17:8-13. When one of these courts rendered a decision, it was as binding as any law given by God himself – even to the extent of exacting the death penalty. What they bound on earth, was bound in heaven.

This is not to say that their authority extended into the established church of Jesus Christ. That authority, Jesus explicitly granted to the Apostles:

Assuredly, I say to you, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven. Again I say to you that if two of you agree on earth concerning anything that they ask, it will be done for them by My Father in heaven. For where two or three are gathered together in My name, I am there in the midst of them (Matthew 18:18-20).

Like the Sanhedrin, the apostles were granted the authority to make decisions within the law. They did not have the authority to go beyond the law. Like the Sanhedrin, they received the Holy Spirit to guide them:

And when He had said this, He breathed on them, and said to them, “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained” (John 20:22, 23).

That spirit was poured out upon them at Pentecost that year, and they prophesied, just as Moses’ Sanhedrin had done (see Numbers 11:24 ff.). From ancient times, the Sanhedrin had the authority to make the rules and observations that sanctified the Hebrew calendar. Jesus and the Apostles seem to have accepted their authority in this area. While there is ample evidence that the early Christians kept the holy days, there is no hint in the New Testament that they ever attempted to sanctify a calendar apart from the normative Hebrew calendar.

The Sanhedrin had always kept the rules for the calendar secret – perhaps with some wisdom. There will always be someone ready to argue with the rules, and the calendar could have been a source of endless bickering. In the fourth century, the patriarch of the Jewish religion published the hitherto secret rules and set up a system whereby the calendar could be predicted far into the future. Prediction, in the final analysis, is the work of the calendar. Most Christian groups that observe the biblical festivals, with few exceptions, have accepted that calendar as the basis for their religious year.

Among those Christians who observe the annual holydays of the Bible, the question is often raised as to whether they should, in some way, observe the new moons. At present, there is nothing to do on the new moons. The holy days are declared to be Sabbath days – work is prohibited except for the preparation of food. There is also a commanded assembly on each of the annual holy days. There are no such requirements connected with the new moons.

There were, however, specific requirements of the priests on these days. Trumpets were to be blown, and large numbers of sacrifices were required (Numbers 10:10; 28:11 ff.). The killing of sacrifices provided a lot of meat to be eaten, so the new moon was a feast of sorts (see 1 Samuel 20). Beyond the work of the priests, though, there were no statutory requirements of the people. We can infer, nevertheless, that the new moons became an important part of the system of festival and worship, and that they will be again. Looking ahead to the Kingdom of God, Isaiah says, “And it shall come to pass, that from one new moon to another, and from one sabbath to another, shall all flesh come to worship before me, saith the LORD” (Isaiah 66:23 KJV).

When the Temple was there, the new moons became days of special worship even though there was no command to do so. The activity of the priests, the special sacrifices, and the festive air made it so. Perhaps they will again when a temple is rebuilt.

The ministry of the vast majority of festival observing churches decided long ago to accept the published Hebrew calendar as the basis for the sacred year. The calendar is published by various Jewish sources, notably The Comprehensive Hebrew Calendar, by Spier. Methods of calculation are discussed there as well as in The Jewish Encyclopedia.

Author

Ronald L. Dart

People around the world have come to appreciate Ron’s easy style, his non-combative approach to explaining the Bible, and the personal, almost one-on-one method of explaining what’s going on in the world in the light of the Bible. After retiring from teaching and church administration in 1995 he started Christian Educational Ministries and the Born to Win radio program.